(1) Field of the Invention
This invention includes stable and useful drugs and pro-drugs that are N6 heterocyclic 5xe2x80x2-thio modified adenosine derivatives. The compositions of this invention are selective, partial or full adenosine A1 receptor agonists, and as such, are useful for modifying cardiac activity, modifying adipocyte function, treating central nervous system disorders, and treating diabetic disorders and obesity in mammals, and especially in humans.
(2) Description of the Art
There are at least two subtypes of adenosine receptors in the heart: A1 and A2A. Each subtype affects different physiological functions. The A1 adenosine receptor mediates two distinct physiological responses. Inhibition of the cardiostimulatory effects of catecholamine are mediated via the inhibition of adenylate cyclase, whereas the direct effects to slow the heart rate (HR) and to prolong impulse propagation through the AV node are due in great part to activation of IKAdo. (B. Lerman and L. Belardinelli Circulation, Vol. 83 (1991), P 1499-1509 and J. C. Shryock and L. Belardinelli The Am. J. Cardiology, Vol. 79 (1997) P 2-10). Both, the anti-xcex2-adrenergic action and direct depressant effects on SA and AV nodal function are mediated by the A1 receptor; there is no role for the A2A receptor in this response to adenosine. A2A receptors mediate the coronary vasodilatation caused by adenosine. Stimulation of the A1 adenosine receptor accordingly shortens the duration and decreases the amplitude of the action potential of AV nodal cells, and hence prolongs the refractory period of the AV nodal cell. The consequence of these effects is to limit the number of impulses conducted from the atria to the ventricles. This forms the basis of the clinical utility of A1 receptor agonists for the treatment of supraventricular tachycardias, including termination of nodal re-entrant tachycardias, and control of ventricular rate during atrial fibrillation and flutter.
A clinical utility of A1 agonists therefore is in the treatment of acute and chronic disorders of heart rhythm, especially those diseases characterized by rapid heart rate where the rate is driven by abnormalities in the sinoatrial, atria, and AV nodal tissues. Such disorders include but are not limited to atrial fibrillation, supraventricular tachycardia and atrial flutter. Exposure to A1 agonists causes a reduction in the heart rate and a regularization of the abnormal rhythm thereby improving cardiovascular function.
A1 agonists, through their ability to inhibit the effects of catecholamines, decrease cellular cAMP, and thus, should have beneficial effects in the failing heart where increased sympathetic tone increases cellular cAMP levels. The latter has been shown to be associated with increased likelihood of ventricular arrhythmias and sudden death. All of the above concepts are discussed in reviews regarding the effects of adenosine on cardiac electrophysiology (see B. Lerman and L. Belardinelli Circulation, Vol. 83 (1991), P 1499-1509 and J. C. Shryock and L. Belardinelli, Am. J. Cardiology, Vol. 79 (1997) P 2-10).
A controversial area in the field of A1 adenosine agonism is that the benefit of preconditioning of the heart prior to ischemia may be due to binding of adenosine to the A1 receptor. Evidence for this hypothesis comes from a rabbit ischemia model wherein 2-chloro-N6-cyclopentyladenosine (CCPA) and R-PIA were administered prior to ischemia providing protection with respect to infarct size (J. D. Thornton et al. Circulation Vol. 85 (1992) 659-665).
A1 agonists, as a result of their inhibitory action on cyclic AMP generation, have antilipolytic effects in adipocytes that leads to a decreased release of nonesterified fatty acids (NEFA) (E. A. van Schaick et al J. Pharmacokinetics and Biopharmaceutics, Vol. 25 (1997) p 673∫694 and P. Strong Clinical Science Vol. 84 (1993) p. 663-669). Non-insulin-dependent diabetes mellitus (NIDDM) is characterized by an insulin resistance that results in hyperglycemia. Factors contributing to the observed hyperglycemia are a lack of normal glucose uptake and activation of skeletal muscle glycogen synthase (GS). Elevated levels of NEFA have been shown to inhibit insulin-stimulated glucose uptake and glycogen synthesis (D. Thiebaud et al Metab. Clin. Exp. Vol. 31 (1982) p 1128-1136 and G. Boden et al J. Clin. Invest. Vol. 93 (1994) p 2438-2446). The hypothesis of a glucose fatty acid cycle was proposed by P. J. Randle as early as 1963 (P. J. Randle et al Lancet (1963) p. 785-789). A tenet of this hypothesis would be that limiting the supply of fatty acids to the peripheral tissues should promote carbohydrate utilization (P. Strong et al Clinical Science Vol. 84 (1993) p. 663-669).
The benefit of an A1 agonist in central nervous disorders has been reviewed and the content are included herein by reference (L. J. S. Knutsen and T. F. Murray In Purinergic Approaches in Experimental Therapeutics, Eds. K. A. Jacobson and M. F. Jarvis (1997) Wiley-Liss, N. Y., P -423-470). Briefly, based on experimental models of epilepsy, a mixed A2A: A1 agonist, metrifudil, has been shown to be a potent anticonvulsant against seizures induced by the inverse benzodiazepine agonist methyl 6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM, H. Klitgaard Eur. J. Pharmacol. (1993) Vol. 224 p. 221-228). In other studies using CGS 21680, an A2A agonist, it was concluded that the anticonvulsant activity was attributed to activation of the A1 receptor (G. Zhang et al. Eur. J. Pharmacol. Vol. 255 (1994) p. 239-243). Furthermore, A1 adenosine selective agonists have been shown to have anticonvulsant activity in the DMCM model (L. J. S. Knutsen In Adenosine and Adenne Nucleotides: From Molecular Biology to Integrative Physiology; eds. L. Belardinelli and A. Pelleg, Kluwer: Boston, 1995, pp 479-487). A second area where an A1 adenosine agonist has a benefit is in animal models of forebrain ishemia as demonstrated by Knutsen et al (J. Med. Chem. Vol. 42 (1999) p. 3463-3477). The benefit in neuroprotection is believed to be in part due to the inhibition of the release of excitatory amino acids (ibid).
There are a number of full A1 agonists disclosed in the prior art. However, the agonists disclosed are generally in the forms that are not useful in the mammalian body. Because useful forms of A1 agonists may not always be stable, soluble or they may have other properties that make their incorporation into therapeutic dosage forms difficult, it is often necessary to identify compositions that are more easily incorporated into therapeutic dosage forms in order to provide the desired therapeutic effect. Also, these agonists fail as useful therapeutics due to side effects caused by the non-selective stimulation of the A1 adenosine receptor in all biologically available tissues and the desensitization of the desired response preempting their use as chronic agents. Therefore, there remains a need for specific and selective A1 agonists, precursors and/or pro-drugs that are converted in the body into useful therapeutic compositions.
In one aspect, this invention includes heterocyclic 5xe2x80x2-thio modified adenosine derivative compositions that are useful partial or full adenosine A1 receptor agonists.
In another aspect, this invention includes pharmaceutical compositions including one or more heterocyclic 5xe2x80x2-thio modified adenosine derivative compositions that are well tolerated with few side effects.
In still another embodiment, this invention includes heterocyclic 5xe2x80x2-thio modified adenosine derivatives having the formula: 
In yet another embodiment, this invention includes methods for administering compositions of this invention to mammals, and especially to humans, to stimulate coronary activity, to modify adipocyte function, to treat central nervous system disorders, and to treat diabetic disorders.
In a further embodiment, this invention is pharmaceutical compositions of matter comprising at least one composition of this invention and one or more pharmaceutical excipients.
This invention includes a class of heterocyclic 5xe2x80x2-thio modified adenosine derivatives having the formula having the formula: 
wherein X1=S, S(O), S(O2);
wherein R1 is a monocyclic or polycyclic heterocyclic group containing from 3 to 15 carbon atoms wherein at least one carbon atom is substituted with an atom or molecule selected from the group consisting of N, O, P and Sxe2x80x94(O)0-2 and wherein R1 does not contain an epoxide group, and wherein R2 is selected from the group consisting of hydrogen, halo, CF3, and cyano; wherein R3 and R4 are independently selected from the group consisting of hydrogen, and xe2x80x94(CO)xe2x80x94Rxe2x80x2 and xe2x80x94(CO)xe2x80x94Rxe2x80x3 wherein Rxe2x80x2 and Rxe2x80x3 are independently selected from the group consisting of C1-15 alkyl, C2-15 alkenyl, C2-15 alkynyl, heterocyclyl, aryl, and heteroaryl, which alkyl, alkenyl, alkynyl, aryl, heterocyclyl, and heteroaryl are optionally substituted with 1 to 3 substituents independently selected from the group of halo, NO2, heterocyclyl, aryl, heteroaryl, CF3, CN, OR20, SR20, S(O)R22, SO2R22, SO2N(R20)2, SO2NR20COR22, SO2NR20CO2R22, SO2NR20CON(R20)2, N(R20)2, NR20COR22, NR20CO2R22, NR20CON(R20)2, NR20C(NR20)NHR23, COR20, CO2R20, CON(R20)2, CONR20SO2R22, NR20SO2R22, SO2NR20CO2R22, OCONR20SO2R22, OC(O)R20, C(O)OCH2OC(O)R20, and OCON(R20)2 and each optional heteroaryl, aryl, and heterocyclyl substituent is optionally substituted with halo, NO2, alkyl, CF3, amino, mono- or di-alkylamino, alkyl or aryl or heteroaryl amide, NR20COR22, NR20SO2R22, COR20, CO2R20, CON(R20)2, NR20CON(R20)2, OC(O)R20, OC(O)N(R20)2, SR20, S(O)R22, SO2R22, SO2N(R20)2, CN, or OR20;
wherein R5 is selected from the group consisting of C1-15 alkyl, C2-15 alkenyl, C2-15 alkynyl, heterocyclyl, aryl, and heteroaryl, wherein alkyl, alkenyl, alkynyl, aryl, heterocyclyl, and heteroaryl are optionally substituted with 1 to 3 substituents independently selected from the group consisting of halo, alkyl, NO2, heterocyclyl, aryl, heteroaryl, CF3, CN, OR20, SR20, S(O)3R20, S(O)R22, SO2R22, SO2N(R20)2, SO2NR20COR22, SO2NR20CO2R22, SO2NR20CON(R20)2, P(O)(OR20)2, N(R20)2, NR20COR22, NR20CO2R22, NR20CON(R20)2, NR20C(NR20)NHR23, COR20, CO2R20, CON(R20)2, CONR20SO2R22, NR20SO2R22, SO2NR20CO2R22, OCONR20SO2R22, OC(O)R20, C(O)OCH2OC(O)R20, and OCON(R20)2 and wherein optional heteroaryl, aryl, and heterocyclyl substituent is optionally substituted with halo, NO2, alkyl, CF3, amino, mono- or di-alkylamino, alkyl or aryl or heteroaryl amide, NR20COR22, NR20SO2R22, COR20, CO2R20, CON(R20)2, NR20CON(R20)2, OC(O)R20, OC(O)N(R20)2, SR20, S(O)R22, SO2R22, SO2N(R20)2, CN, or OR20;
wherein R20 is a member selected from the group consisting of H, C1-15 alkyl, C2-15 alkenyl, C2-15 alkynyl, heterocyclyl, aryl, and heteroaryl, which alkyl, alkenyl, alkynyl, heterocyclyl, aryl, and heteroaryl are optionally substituted with 1 to 3 substituents independently selected from halo, alkyl, mono- or dialkylamino, alkyl or aryl or heteroaryl amide, CN, Oxe2x80x94C1-C6 alkyl, CF3, aryl, and heteroaryl; and
R22 is a member selected from the group consisting of C1-15 alkyl, C2-15 alkenyl, C2-15 alkynyl, heterocyclyl, aryl, and heteroaryl, which alkyl, alkenyl, alkynyl, heterocyclyl, aryl, and heteroaryl are optionally substituted with 1 to 3 substituents independently selected from halo, alkyl, mono- or dialkylamino, alkyl or aryl or heteroaryl amide, CN, Oxe2x80x94C1-6 alkyl, CF3, and heteroaryl.
In preferred compositions, X1=S or SO2; R2 is a hydrogen; R3 and R4 are each independently selected from the group consisting of hydrogen, xe2x80x94(CO)xe2x80x94Rxe2x80x2 and xe2x80x94(CO)xe2x80x94Rxe2x80x3 wherein Rxe2x80x2 and Rxe2x80x3 are each independently selected from the group consisting of C1-6 alkyl and, more preferably, R3 and R4 are each hydrogen; R5 is selected from the group consisting of C1-8 alkyl, and aryl wherein alkyl, and aryl are optionally substituted with from 1 to 2 substituents independently selected from the group consisting of halo, alkyl, aryl, heteroaryl, CF3, CN, OR20, S(O)R22, SO2R22, SO2N(R20)2, NR20CON(R20)2, CO2R20, CON(R20)2, and wherein each optional heteroaryl, and aryl substituent is further optionally substituted with halo, alkyl, CF3, CO2R20, CN, and OR20; R20 is selected from the group consisting of H, C1-6 alkyl; and R22 is selected from the group consisting of C1-6. In the above compositions, R5 is more preferably selected from the group consisting of C1-8 alkyl, and aryl wherein alkyl, and aryl are optionally substituted with from 1 to 2 substituents independently selected from the group consisting of halo, alkyl, CF3, and OR20.
In more preferred compositions, X1=S or SO2; R2 is a hydrogen; R3 and R4 are independently selected from the group consisting of hydrogen, xe2x80x94(CO)xe2x80x94Rxe2x80x2 and xe2x80x94(CO)xe2x80x94Rxe2x80x3 wherein Rxe2x80x2 and Rxe2x80x3 are each independently selected from the group consisting of C1-16 alkyl which alkyl are optionally substituted with 1 substituent selected from the group consisting of aryl, CF3, CN, OR20, N(R20)2, and wherein each optional aryl substituent is further optionally substituted with halo, NO2, alkyl, CF3; R5 is C1-8 alkyl, wherein alkyl, is optionally substituted with from 1 to 2 substituents independently selected from the group consisting of halo, alkyl, aryl, heteroaryl, CF3, CN, OR20, S(O)R22, SO2R22, SO2N(R20)2, NR20CON(R20)2, CO2R20, CON(R20)2, wherein each optional heteroaryl, and aryl substituent is further optionally substituted with halo, alkyl, CF3, CO2R20, CN, and OR20; R20 is selected from the group consisting of H, C1-6 alkyl; and R22 is selected from the group consisting of C1-6. In the above compositions, R5 is more preferably C1-8 alkyl that is optionally substituted with from 1 to 2 substituents independently selected from the group consisting of aryl, heteroaryl, OR20, S(O)R22, CO2R20, CON(R20)2, and wherein each optional heteroaryl, and aryl substituent is further optionally substituted with halo, alkyl, CF3, CO2R20, CN, and OR20, and R5 is even more preferably C1-8 alkyl that is optionally substituted with 1 substituent selected from the group consisting of CO2R20, and CON(R20)2, and R5 is even more preferably C1-6 alkyl and most preferably methyl or ethyl or isopropyl. Also in the above compositions, R3 and R4 are more preferably each hydrogen and R20 is more preferably selected from the group consisting of H, and methyl.
In another class of preferred compositions, R2 is a hydrogen; R3 and R4 are each independently selected from the group consisting of hydrogen,xe2x80x94(CO)xe2x80x94Rxe2x80x2 and xe2x80x94(CO)xe2x80x94Rxe2x80x3 wherein each Rxe2x80x2 and Rxe2x80x3 are independently selected from the group consisting of C1-6 alkyl, and aryl, which alkyl and aryl are optionally substituted with from 1 to 2 substituents independently selected from the group of halo, NO2, aryl, CF3, CN, OR20, N(R20)2, S(O)R22, SO2R22, wherein each optional aryl substituent is further optionally substituted with halo, NO2, alkyl, CF3; R5 is selected from the group consisting of, aryl, and heteroaryl, wherein aryl, and heteroaryl are optionally substituted with from1 to 3 substituents independently selected from the group consisting of halo, alkyl, aryl, heteroaryl, CF3, CN, OR20, SR20, N(R2)2, S(O)R22, SO2R22, SO2N(R20)2, NR20CO2R22, NR20CON(R20)2, CO2R20, CON(R20)2, and wherein each optional heteroaryl, and aryl substituent is further optionally substituted with halo, alkyl, CF3, CO2R20, CON(R20)2, S(O)R22, SO2R22, SO2N(R20)2, CN, or OR20; R20 is selected from the group consisting of H, C1-6 alkyl, and aryl, which alkyl and aryl are optionally substituted with 1 substituent selected from halo, alkyl, mono- or dialkylamino, CN, Oxe2x80x94C1-6 alkyl, CF3; and R22 is selected from the group consisting of C1-6 alkyl and aryl, which alkyl and aryl are optionally substituted with 1 substituent selected from halo, alkyl or CN, Oxe2x80x94C1-6 alkyl, and CF3. In the above compositions, X1 is preferably S; R3 and R4 are more preferably hydrogen; R5 is more preferably selected from the group consisting of, aryl, and heteroaryl, wherein aryl, and heteroaryl are optionally substituted with from 1 to 3 substituents independently selected from the group consisting of halo, alkyl, CF3, CN, OR20, SR20, CO2R20, CON(R20)2. Even more preferably R5 is aryl that is optionally substituted with from 1 to 2 substituents independently selected from the group consisting of halo, alkyl, CF3, OR20, CO2R20, CON(R20)2. And most preferably, R5 is phenyl that is optionally substituted with a substituent selected from the group consisting of methoxy, chloro, fluoro, methyl, and trifluoromethyl. In the compounds above, R20 is preferably selected from the group consisting of H, C1-3 alkyl and most preferably H or methyl while R22 is preferably selected from the group consisting of C1-6 alkyl.
In the compositions of this invention, R1 is preferably mono or polysubstituted with one or more compounds selected from the group consisting of halogen, oxo, hydroxyl, lower alkyl, substituted lower alkyl, alkoxy, aryl, acyl, aryloxy, carboxyl, substituted aryl, heterocycle, heteroaryl, substituted heteroaryl, cycloalkyl, substituted cycloalkyl, nitro, cyano and mixtures thereof. More preferably, R1 is a monocyclic, bicyclic, or tricyclic cycloalkyl group containing from 3 to 15 carbon atoms wherein at least one carbon atom is substituted with an atom or molecule selected from the group consisting of O or Sxe2x80x94(O)0-2. Some examples of preferred R1 moieties include: 
wherein Rxe2x80x2 and Rxe2x80x3 may each individually be selected from the group halogen, hydroxyl, lower alkyl, substituted lower alkyl, alkoxy, aryl, acyl, aryloxy, carboxyl, substituted aryl, heterocycle, heteroaryl, substituted heteroaryl, cycloalkyl, substituted cycloalkyl, nitro, and cyano, and X is O, or S(xe2x80x94O)0-2, alternately, CRxe2x80x2Rxe2x80x3 may be Cxe2x95x90O. More preferably, Rxe2x80x2 and Rxe2x80x3 are each individually selected from the group hydrogen, lower alkyl, and substituted lower alkyl. In the compositions above, each R is individually selected from the group consisting of H, lower alkyl, and substituted lower alkyl.
Most preferred compounds of this invention include, 2-{6-[((3R)oxolan-3-yl)amino]purin-9-yl}(4S,5S,2R,3R)-5-(methylthiomethyl)oxolane-3,4-diol; 2-{6-[((3R)oxolan-3-yl)amino]purin-9-yl}(4S,5S,2R,3R)-5-[(Ethylthio)methyl]oxolane-3,4-diol; 2-{6-[((3R)oxolan-3-yl)amino]purin-9-yl}(4S,5S,2R,3R)-5-[(Methylethylthio)methyl]oxolane-3,4-diol; 2-{6-[((3R)oxolan-3-yl)amino]purin-9-yl}(4S,5S,2R,3R)-5-(phenylthiomethyl)oxolane-3,4diol; 2-{6-[((3R)oxolan-3-yl)amino]purin-9-yl}(4S,5S,2R,3R)-5-[(4-Methoxyphenylthio)methyl]oxolane-3,4-diol; 2-{6-[((3R)oxolan-3-yl)amino]purin-9-yl}(4S,5S,2R,3R)-5-[(4-chlorophenylthio)methyl]oxolane-3,4-diol; 2-{6-[((3R)oxolan-3-yl)amino]purin-9-yl}(4S,5S,2R,3R)-5-[(4-fluorophenylthio)methyl]oxolane-3,4-diol; 2-{6-[((3R)oxolan-3-yl)amino]purin-9-yl}(4S,5S,2R,3R)-5-[(4-methylphenylthio)methyl]oxolane-3,4-diol; 2-{6-[((3R)oxolan-3-yl)amino]purin-9-yl}(4S,5S,2R,3R)-5-[(4-(trifluoromethyl)phenylthio)methyl]oxolane-3,4-diol; 2-{6-[((3R)oxolan-3-yl)amino]purin-9-yl}(4S,5S,2R,3R)-5-[(2-methoxyphenylthio)methyl]oxolane-3,4-diol; and (5-{6-[((3R)oxolan-3-yl)amino]purinyl-9-yl}(2S,3S,4R,5R)-3,4-dihydroxyoxolan-2-yl)(ethylsulfonyl)methane.
The following definitions apply to terms as used herein.
xe2x80x9cHaloxe2x80x9d or xe2x80x9cHalogenxe2x80x9dxe2x80x94alone or in combination means all halogens, that is, chloro (Cl), fluoro (F), bromo (Br), iodo (I).
xe2x80x9cHydroxylxe2x80x9d refers to the group xe2x80x94OH.
xe2x80x9cThiolxe2x80x9d or xe2x80x9cmercaptoxe2x80x9d refers to the group xe2x80x94SH.
xe2x80x9cAlkylxe2x80x9dxe2x80x94alone or in combination means an alkane-derived radical containing from 1 to 20, preferably 1 to 15, carbon atoms (unless specifically defined). It is a straight chain alkyl, branched alkyl or cycloalkyl. Preferably, straight or branched alkyl groups containing from 1-15, more preferably 1 to 8, even more preferably 1-6, yet more preferably 1-4 and most preferably 1-2, carbon atoms, such as methyl, ethyl, propyl, isopropyl, butyl, t-butyl and the like. The term xe2x80x9clower alkylxe2x80x9d is used herein to describe the straight chain alkyl groups described immediately above. Preferably, cycloalkyl groups are monocyclic, bicyclic or tricyclic ring systems of 3-8, more preferably 3-6, ring members per ring, such as cyclopropyl, cyclopentyl, cyclohexyl, adamantyl and the like. Alkyl also includes a straight chain or branched alkyl group that contains or is interrupted by a cycloalkyl portion. The straight chain or branched alkyl group is attached at any available point to produce a stable compound. Examples of this include, but are not limited to, 4-(isopropyl)-cyclohexylethyl or 2-methyl-cyclopropylpentyl. A substituted alkyl is a straight chain alkyl, branched alkyl, or cycloalkyl group defined previously, independently substituted with 1 to 3 groups or substituents of halo, hydroxy, alkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, acyloxy, aryloxy, heteroaryloxy, amino optionally mono- or di-substituted with alkyl, aryl or heteroaryl groups, amidino, urea optionally substituted with alkyl, aryl, heteroaryl or heterocyclyl groups, aminosulfonyl optionally N-mono- or N,N-di-substituted with alkyl, aryl or heteroaryl groups, alkylsulfonylamino, arylsulfonylamino, heteroarylsulfonylamino, alkylcarbonylamino, arylcarbonylamino, heteroarylcarbonylamino, or the like.
xe2x80x9cAlkenylxe2x80x9dxe2x80x94alone or in combination means a straight, branched, or cyclic hydrocarbon containing 2-20, preferably 2-17, more preferably 2-10, even more preferably 2-8, most preferably 2-4, carbon atoms and at least one, preferably 1-3, more preferably 1-2, most preferably one, carbon to carbon double bond. In the case of a cycloalkyl group, conjugation of more than one carbon to carbon double bond is not such as to confer aromaticity to the ring. Carbon to carbon double bonds may be either contained within a cycloalkyl portion, with the exception of cyclopropyl, or within a straight chain or branched portion. Examples of alkenyl groups include ethenyl, propenyl, isopropenyl, butenyl, cyclohexenyl, cyclohexenylalkyl and the like. A substituted alkenyl is the straight chain alkenyl, branched alkenyl or cycloalkenyl group defined previously, independently substituted with 1 to 3 groups or substituents of halo, hydroxy, alkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, acyloxy, aryloxy, heteroaryloxy, amino optionally mono- or di-substituted with alkyl, aryl or heteroaryl groups, amidino, urea optionally substituted with alkyl, aryl, heteroaryl or heterocyclyl groups, aminosulfonyl optionally N-mono- or N,N-di-substituted with alkyl, aryl or heteroaryl groups, alkylsulfonylamino, arylsulfonylamino, heteroarylsulfonylamino, alkylcarbonylamino, arylcarbonylamino, heteroarylcarbonylamino, carboxy, alkoxycarbonyl, aryloxycarbonyl, heteroaryloxycarbonyl, or the like attached at any available point to produce a stable compound.
xe2x80x9cAlkynylxe2x80x9dxe2x80x94alone or in combination means a straight or branched hydrocarbon containing 2-20, preferably 2-17, more preferably 2-10, even more preferably 2-8, most preferably 2-4 carbon atoms containing at least one, preferably one, carbon to carbon triple bond. Examples of alkynyl groups include ethynyl, propynyl, butynyl and the like. A substituted alkynyl refers to the straight chain alkynyl or branched alkenyl defined previously, independently substituted with 1 to 3 groups or substituents of halo, hydroxy, alkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, acyloxy, aryloxy, heteroaryloxy, amino optionally mono- or di-substituted with alkyl, aryl or heteroaryl groups, amidino, urea optionally substituted with alkyl, aryl, heteroaryl or heterocyclyl groups, aminosulfonyl optionally N-mono- or N,N-di-substituted with alkyl, aryl or heteroaryl groups, alkylsulfonylamino, arylsulfonylamino, heteroarylsulfonylamino, alkylcarbonylamino, arylcarbonylamino, heteroarylcarbonylamino, or the like attached at any available point to produce a stable compound.
xe2x80x9cAlkyl alkenylxe2x80x9d refers to a group xe2x80x94Rxe2x80x94CRxe2x80x2xe2x95x90CRxe2x80x2xe2x80x3Rxe2x80x3xe2x80x3, where R is lower alkyl, or substituted lower alkyl, Rxe2x80x2, Rxe2x80x2xe2x80x3, Rxe2x80x3xe2x80x3 may independently be hydrogen, halogen, lower alkyl, substituted lower alkyl, acyl, aryl, substituted aryl, hetaryl, or substituted hetaryl as defined below.
xe2x80x9cAlkyl alkynylxe2x80x9d refers to a groups xe2x80x94RC CRxe2x80x2 where R is lower alkyl or substituted lower alkyl, Rxe2x80x2 is hydrogen, lower alkyl, substituted lower alkyl, acyl, aryl, substituted aryl, hetaryl, or substituted hetaryl as defined below.
xe2x80x9cAlkoxyxe2x80x9d denotes the group xe2x80x94OR, where R is lower alkyl, substituted lower alkyl, acyl, aryl, substituted aryl, aralkyl, substituted aralkyl, heteroalkyl, heteroarylalkyl, cycloalkyl, substituted cycloalkyl, cycloheteroalkyl, or substituted cycloheteroalkyl as defined.
xe2x80x9cAlkylthioxe2x80x9d denotes the group xe2x80x94SR, xe2x80x94S(O)n=1-2xe2x80x94R, where R is lower alkyl, substituted lower alkyl, aryl, substituted aryl, aralkyl or substituted aralkyl as defined herein.
xe2x80x9cAcylxe2x80x9d denotes groups xe2x80x94C(O)R, where R is hydrogen, lower alkyl substituted lower alkyl, aryl, substituted aryl and the like as defined herein.
xe2x80x9cAryloxyxe2x80x9d denotes groups xe2x80x94OAr, where Ar is an aryl, substituted aryl, heteroaryl, or substituted heteroaryl group as defined herein.
xe2x80x9cAminoxe2x80x9d denotes the group NRRxe2x80x2, where R and Rxe2x80x2 may independently by hydrogen, lower alkyl, substituted lower alkyl, aryl, substituted aryl, hetaryl, or substituted hetaryl as defined herein or acyl.
xe2x80x9cAmidoxe2x80x9d denotes the group xe2x80x94C(O)NRRxe2x80x2, where R and Rxe2x80x2 may independently by hydrogen, lower alkyl, substituted lower alkyl, aryl, substituted aryl, hetaryl, substituted hetaryl as defined herein.
xe2x80x9cCarboxylxe2x80x9d denotes the group xe2x80x94C(O)OR, where R is hydrogen, lower alkyl, substituted lower alkyl, aryl, substituted aryl, hetaryl, and substituted hetaryl as defined herein.
xe2x80x9cArylxe2x80x9dxe2x80x94alone or in combination means phenyl or naphthyl optionally carbocyclic fused with a cycloalkyl of preferably 5-7, more preferably 5-6, ring members and/or optionally substituted with 1 to 3 groups or substituents of halo, hydroxy, alkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, acyloxy, aryloxy, heteroaryloxy, amino optionally mono- or di-substituted with alkyl, aryl or heteroaryl groups, amidino, urea optionally substituted with alkyl, aryl, heteroaryl or heterocyclyl groups, aminosulfonyl optionally N-mono- or N,N-di-substituted with alkyl, aryl or heteroaryl groups, alkylsulfonylamino, arylsulfonylamino, heteroarylsulfonylamino, alkylcarbonylamino, arylcarbonylamino, heteroarylcarbonylamino, or the like.
xe2x80x9cSubstituted arylxe2x80x9d refers to aryl optionally substituted with one or more functional groups, e.g., halogen, lower alkyl, lower alkoxy, alkylthio, acetylene, amino, amido, carboxyl, hydroxyl, aryl, aryloxy, heterocycle, hetaryl, substituted hetaryl, nitro, cyano, thiol, sulfamido and the like.
xe2x80x9cHeterocyclexe2x80x9d refers to a saturated, unsaturated, or aromatic carbocyclic group having a single ring (e.g., morpholino, pyridyl or furyl) or multiple condensed rings (e.g., naphthpyridyl, quinoxalyl, quinolinyl, indolizinyl or benzo[b]thienyl) and having at least one hetero atom, such as N, O, P, or Sxe2x80x94(O)0-2, within the ring, which can optionally be unsubstituted or substituted with, e.g., halogen, lower alkyl, lower alkoxy, alkylthio, acetylene, amino, amido, carboxyl, hydroxyl, aryl, aryloxy, heterocycle, hetaryl, substituted hetaryl, nitro, cyano, thiol, sulfamido and the like.
xe2x80x9cHeteroarylxe2x80x9dxe2x80x94alone or in combination means a monocyclic aromatic ring structure containing 5 or 6 ring atoms, or a bicyclic aromatic group having 8 to 10 atoms, containing one or more, preferably 1-4, more preferably 1-3, even more preferably 1-2, heteroatoms independently selected from the group O, S, and N, and optionally substituted with1 to 3 groups or substituents of halo, hydroxy, alkoxy, alkylthio, alkylsulfinyl, alkylsulfonyl, acyloxy, aryloxy, heteroaryloxy, amino optionally mono- or di-substituted with alkyl, aryl or heteroaryl groups, amidino, urea optionally substituted with alkyl, aryl, heteroaryl or heterocyclyl groups, aminosulfonyl optionally N-mono- or N,N-di-substituted with alkyl, aryl or heteroaryl groups, alkylsulfonylamino, arylsulfonylamino, heteroarylsulfonylamino, alkylcarbonylamino, arylcarbonylamino, heteroarylcarbonylamino, or the like. Heteroaryl is also intended to include oxidized S or N, such as sulfinyl, sulfonyl and N-oxide of a tertiary ring nitrogen. A carbon or nitrogen atom is the point of attachment of the heteroaryl ring structure such that a stable aromatic ring is retained. Examples of heteroaryl groups are pyridinyl, pyridazinyl, pyrazinyl, quinazolinyl, purinyl, indolyl, quinolinyl, pyrimidinyl, pyrrolyl, oxazolyl, thiazolyl, thienyl, isoxazolyl, oxathiadiazolyl, isothiazolyl, tetrazolyl, imidazolyl, triazinyl, furanyl, benzofuryl, indolyl and the like. A substituted heteroaryl contains a substituent attached at an available carbon or nitrogen to produce a stable compound.
xe2x80x9cHeterocyclylxe2x80x9dxe2x80x94alone or in combination means a non-aromatic cycloalkyl group having from 5 to 10 atoms in which from 1 to 3 carbon atoms in the ring are replaced by heteroatoms of O, S or N, and are optionally benzo fused or fused heteroaryl of 5-6 ring members and/or are optionally substituted as in the case of cycloalkyl. Heterocycyl is also intended to include oxidized S or N, such as sulfinyl, sulfonyl and N-oxide of a tertiary ring nitrogen. The point of attachment is at a carbon or nitrogen atom. Examples of heterocyclyl groups are tetrahydrofuranyl, dihydropyridinyl, piperidinyl, pyrrolidinyl, piperazinyl, dihydrobenzofuryl, dihydroindolyl, and the like. A substituted hetercyclyl contains a substituent nitrogen attached at an available carbon or nitrogen to produce a stable compound.
xe2x80x9cSubstituted heteroarylxe2x80x9d refers to a heterocycle optionally mono or poly substituted with one or more functional groups, e.g., halogen, lower alkyl, lower alkoxy, alkylthio, acetylene, amino, amido, carboxyl, hydroxyl, aryl, aryloxy, heterocycle, substituted heterocycle, hetaryl, substituted hetaryl, nitro, cyano, thiol, sulfamido and the like.
xe2x80x9cAralkylxe2x80x9d refers to the group xe2x80x94Rxe2x80x94Ar where Ar is an aryl group and R is lower alkyl or substituted lower alkyl group. Aryl groups can optionally be unsubstituted or substituted with, e.g., halogen, lower alkyl, alkoxy, alkylthio, acetylene, amino, amido, carboxyl, hydroxyl, aryl, aryloxy, heterocycle, substituted heterocycle, hetaryl, substituted hetaryl, nitro, cyano, thiol, sulfamido and the like.
xe2x80x9cHeteroalkylxe2x80x9d refers to the group xe2x80x94Rxe2x80x94Het where Het is a heterocycle group and R is a lower alkyl group. Heteroalkyl groups can optionally be unsubstituted or substituted with e.g., halogen, lower alkyl, lower alkoxy, alkylthio, acetylene, amino, amido, carboxyl, aryl, aryloxy, heterocycle, substituted heterocycle, hetaryl, substituted hetaryl, nitro, cyano, thiol, sulfamido and the like.
xe2x80x9cHeteroarylalkylxe2x80x9d refers to the group xe2x80x94Rxe2x80x94HetAr where HetAr is an heteroaryl group and R lower alkyl or substituted lower alkyl. Heteroarylalkyl groups can optionally be unsubstituted or substituted with, e.g., halogen, lower alkyl, substituted lower alkyl, alkoxy, alkylthio, acetylene, aryl, aryloxy, heterocycle, substituted heterocycle, hetaryl, substituted hetaryl, nitro, cyano, thiol, sulfamido and the like.
xe2x80x9cCycloalkylxe2x80x9d refers to a divalent cyclic or polycyclic alkyl group containing 3 to 15 carbon atoms.
xe2x80x9cSubstituted cycloalkylxe2x80x9d refers to a cycloalkyl group comprising one or more substituents with, e.g., halogen, lower alkyl, substituted lower alkyl, alkoxy, alkylthio, acetylene, aryl, aryloxy, heterocycle, substituted heterocycle, hetaryl, substituted hetaryl, nitro, cyano, thiol, sulfamido and the like.
xe2x80x9cCycloheteroalkylxe2x80x9d refers to a cycloalkyl group wherein one or more of the ring carbon atoms is replaced with a heteroatom (e.g., N, O, S or P).
Substituted cycloheteroalkylxe2x80x9d refers to a cycloheteroalkyl group as herein defined which contains one or more substituents, such as halogen, lower alkyl, lower alkoxy, alkylthio, acetylene, amino, amido, carboxyl, hydroxyl, aryl, aryloxy, heterocycle, substituted heterocycle, hetaryl, substituted hetaryl, nitro, cyano, thiol, sulfamido and the like.
xe2x80x9cAlkyl cycloalkylxe2x80x9d denotes the group xe2x80x94R-cycloalkyl where cycloalkyl is a cycloalkyl group and R is a lower alkyl or substituted lower alkyl. Cycloalkyl groups can optionally be unsubstituted or substituted with e.g. halogen, lower alkyl, lower alkoxy, alkylthio, acetylene, amino, amido, carboxyl, hydroxyl, aryl, aryloxy, heterocycle, substituted heterocycle, hetaryl, substituted hetaryl, nitro, cyano, thiol, sulfamido and the like.
xe2x80x9cAlkyl cycloheteroalkylxe2x80x9d denotes the group xe2x80x94R-cycloheteroalkyl where R is a lower alkyl or substituted lower alkyl. Cycloheteroalkyl groups can optionally be unsubstituted or substituted with e.g. halogen, lower alkyl, lower alkoxy, alkylthio, amino, amido, carboxyl, acetylene, hydroxyl, aryl, aryloxy, heterocycle, substituted heterocycle, hetaryl, substituted hetaryl, nitro, cyano, thiol, sulfamido and the like.
The compounds of this invention can be prepared as outlined in the schemes 1-5 below. A general outline for the preparation of V and VI is shown in Scheme 1. Compound I can be prepared, following the procedures reported earlier (U.S. Pat. No. 5,789,416, the specification of which is incorporated herein by reference), by reacting 6-chloropurine riboside 1 with a primary amine R1NH2. The 2xe2x80x2, 3xe2x80x2 hydroxy groups can be protected as acetonide by reacting I with 2,2xe2x80x2-dimethoxypropane in the presence of a catalytic amount of TsOH [Evans, Parrish and Long Carbohydrat. Res., 3,453 (1967)] to give II. Activation of the 5xe2x80x2-hydroxyl of II with MsCl in pyridine can give the 5xe2x80x2-mesylate III. Displacement of the 5xe2x80x2-mesylate with R5SNa can give sulfides with the general formula IV. Treatment of IV with an acid can free the 2xe2x80x2, 3xe2x80x2 hydroxyl groups to give sulfide derivatives with the general formula V. Esterification of V can afford 2xe2x80x2, 3xe2x80x2 diesters with the general formula VI. 
The 2-substituted derivatives with the general formula XV can be prepared as shown in Scheme 2. Condensation of 1,2,3,5-tetraacetylribofuranaside 2 with 2-substituted-6-chloropurine VII can give 2-substituted-6-chloropurineriboside triacetate VIII which on reaction with a primary amine R1NH2 can give 2-substituted-6-alkylamino derivatives IX. Hydrolysis of the acetates followed by protection of the 2xe2x80x2, 3xe2x80x2 hydroxy groups as an acetonide can give XI. Activation of the 5xe2x80x2-hydroxyl of XI with MsCl in pyridine can give the 5xe2x80x2-mesylate XII. Displacement of the 5xe2x80x2-mesylate with R5SNa can give sulfides with the general formula XIII that can be deprotected to give sulfides with general formula XIV. 
Oxidation of sulfides with the general formula V, VI, XIV, XV (Scheme 3) with an oxidizing agent (Drabowicz, et.al. The chemistry of sulfones and sulfoxides, Wiley, N.Y., 1988, 233-378) can afford corresponding sulfoxides with the general formula XVI, XVII, XVIII, XIX. These sulfoxides on further oxidation can afford sulfones with the general formula XX, XXI, XXII, XXIII. 
An example of a specific synthesis of one of the compounds of this invention is shown in Scheme 4. Preparation of compound 7 starting from compound 3 is shown in scheme 3. Compound 3 was prepared from 6-chloropurineriboside 1 and 3-(R)-aminotetrahydrofuran following the procedure reported previously (See U.S. Pat. No. 5,789,164). Protection of the 2xe2x80x2 and 3xe2x80x2 hydroxyls with dimethoxypropane in the presence of TsOH(cat.) gave acetonide 4. Reaction of 4 with MsCl in pyridine at 0xc2x0 C. gave mesylate 5 which on displacement with sodium methanethiolate in an acetonitrile/water mixture gave sulfide 6. Deprotection of 6 with 80% acetic acid/water gave the target compound 7. 
Oxidation of the ethyl sulfide 8 with oxone (Trost, B. M.; Curran, D. P. Tetrahedron Letters 1981, 22, 1287) in MeOH gave sulfone 9 (Scheme 5). 
This invention also includes pro-drugs of the A1 agonist compositions of this invention. A pro-drug is a drug which has been chemically modified and may be biologically inactive at its site of action, but which will be degraded or modified by one or more enzymatic or in vivo processes to the bioactive form. The pro-drugs of this invention should have a different pharmacokinetic profile to the parent enabling improved absorption across the mucosal epithelium, better salt formulation and/or solubility and improved systemic stability. The compounds of this invention may be preferably modified at one or more of the hydroxyl groups to form pro-drugs. The modifications may be (1) ester or carbamate derivatives which may be cleaved by esterases or lipases, for example; (2) peptides which may be recognized by specific or non specific proteinase; or (3) derivatives that accumulate at a site of action through membrane selection or a pro-drug form or modified pro-drug form, or any combination of (1) to (3) above.
If a compound of this invention contains a basic group, then corresponding acid addition salt may be prepared. Acid addition salts of the compounds are prepared in a standard manner in a suitable solvent from the parent compound and an excess of acid, such as hydrochloric, hydrobromic, sulfuric, phosphoric, acetic, maleic, succinic, or methanesulfonic. The hydrochloric salt form is especially useful. If a compound of this invention contains an acidic group, then corresponding cationic salts may be prepared. Typically the parent compound is treated with an excess of an alkaline reagent, such as hydroxide, carbonate or alkoxide, containing the appropriate cation. Cations such as Na+, K+, Ca+2 and NH4+ are examples of cations present in pharmaceutically acceptable salts. Certain of the compounds form inner salts or zwitterions which may also be acceptable.
The compositions of this invention are useful for treating a variety of mammalian to disorders and preferably human disorders that are mediated by an A1 adenosine receptor. For example, the compositions of this invention are useful for modifying cardiac activity in mammals experiencing a coronary electrical disorder that can be treated by stimulating an A1 adenosine receptor. Examples of coronary electrical disorders that can be treated by the compositions of this invention include supraventricular tachycardias, atrial fibrillation, atrial flutter, and AV nodal re-entrant tachycardia. Furthermore, orally active A1 agonists of this invention that demonstrate an excellent safety profile in treating supraventricular arrhythmias may also be used as a prophylactic for those at high risk of a myocardial ischemia.
The compositions of this invention are also useful for modifying adipocyte function by stimulating an A1 adenosine receptor that leads to diminished release of NEFA and increased release of leptin. Disease states related to adipocyte function that can be modified using compositions of this invention include diabetes, and obesity.
In skeletal muscle cells, A1 AdoR agonists mediate a synergistic stimulation of glucose uptake and transport by insulin (Vergauwen, L. et al, J. Clin. Invest. 1994, 93, 974-81; Challiss, R. A. et al, Eur.J.Pharacol., 1992, 226, 121-8). Another therapeutic utility of compositions of this invention is more efficient regulation of glucose and a decrease of circulating levels of insulin in patients afflicted with diabetes.
The A1 receptor agonist, R-PIA, has been shown to increase the leptin released from white adipocytes and augment insulin-stimulated leptin production (M. Ozeck Master""s Thesis Univ. of Florida 1999 with L. Belardinelli). Evidence suggests that catecholamines inhibit the production of leptin from adipocytes through activation of xcex2-adrenergic receptors. The anti-xcex2-adrenergic effects of A1 agonists on the adipocytes are believed to play a role in the increased release of leptin. The functional role of leptin is multifaceted including decreased appetite, stimulated energy utilization, and increased fertility.
The compositions of this invention may also be used to provide central nervous system neuroprotection by stimulating an A1 adenosine receptor. Central nervous system disorders that may be treated using the compositions of this invention include epilepsy, and stroke.
In the kidney, there is evidence that stimulation of the A1 AdoR promotes sodium retention, promotes exchange of sodium in urine for potassium, and reduces glomerular filtration rate as sodium excretion increases (Gellai, M. et al, JPET, 1998, 286, 1191-6; Wilcox, C. S. et al, J.Am.Soc.Nephrol., 1999, 10, 714-720). It is believed that these responses are elicited by chronic local production of adenosine. That is, in the kidney there is a tonic effect of adenosine to stimulate the A1 AdoR. Another clinical utility of compositions of this invention, therefore, is the selective antagonism of the A1 AdoR in the kidney to inhibit sodium retention, inhibit the exchange of sodium for potassium, and preserve kidney glomerular filtration rate when sodium excretion rises to yield a potassium sparring diuretic that preserves renal function.
The compositions of this invention are further useful for providing cardiomyocyte protection from ischemic events by stimulating an A1 adenosine receptor. Ischemic events treatable using the compositions of this invention include stable angina, unstable angina, cardiac transplant, and myocardial infarction.
An important aspect of compounds of this invention is that each compound has an intrinsic efficacy associated with it (for a discussion see T. P. Kenakin Stimulus Response Mechanisms. In Pharmacological Analysis of Drug-Receptor Interaction, Ed. Kenakin, T. P. New York: Raven Press, p 39-68). This intrinsic efficacy is not defined by it""s affinity for the receptor, but it is defined as the quantitative effect of the compound to activate a given effector system (eg. cAMP production) in a given cell type. The intrinsic efficacy of a given compound may vary from cell type to cell type and/or from effector system to effector system. When a compound has an intrinsic efficacy lower than a full agonist (i.e. submaximal) than the agonist is called a partial agonist. Thus, a partial agonist is a molecule that binds to a receptor and elicits a response that is smaller than that of a full agonist (submaximal), but also competitively antagonizes the response(s) elicited by a full agonist. The tonic action of adenosine with respect to kidney function is a prime example where a partial A1 agonist be expected to act as antagonists (e.g. adenosine). The tonic action of adenosine with respect to kidney function is a prime example where a partial A1 agonist could be expected to act as an antagonist. The compounds of this invention are believed to have therapeutically useful affinities for the adenosine A1 receptor, and they will have a range of intrinsic efficacies from full agonist to partial agonist. That is, some compounds may have no effect with respect to a given effector system in a given cell type, but be a full agonist in another cell type and/or effector system. The reason for such variable pharmacological behavior relates to the magnitude of the receptor reserve for the A1 adenosine receptor in any given cell type (eg. AV nodal cells vs. adipocytes) and for a given response. The receptor reserve (spare receptor capacity) is the total number of receptors minus the fraction of receptors that is required to induce the maximal response using a full agonist (L. E. Limbird, Cell Surface Receptors: A Short Course on Theory and Methods, Kluwer Acad. Pub. 1996, Boston, Mass.). Therefore, the agonist could be a full agonist at eliciting a response, and a partial agonist for eliciting another response in other tissue or cells and still be an antagonist or lack activity for a third response in another tissue or cell. Consequently, a partial agonist targeted to a selected target is likely to cause fewer side effects than a full agonist. As a corollary, a full agonist elicits all the effects mediated by the respective receptor, whereas this is not necessarily the case of a partial agonist. The compounds of this invention based on their affinity for the A1 receptor and their potency and selectivity to elicit A1 receptor mediated responses have the potential for therapeutic intervention in the multiple disease states described above.
Partial A1 agonists may have an added benefit for chronic therapy because they will be less likely to induce desensitization of the A1 receptor (R. B. Clark, B. J. Knoll, R. Barber TiPS, Vol. 20 (1999) p. 279-286) and to cause side effects. Chronic administration of a full agonist (R-N6-phenylisopropyladenosine, R-PIA) for 7 days led to a desensitization of the A1 receptor in terms of the dromotropic response in guinea pigs (note: a decrease in receptor number was observedxe2x80x94D. M. Dennis, J. C. Shryock, L. Belardinelli JPET, Vol. 272 (1995) p. 1024-1035). The A1 agonist induced inhibitory effect on the production of cAMP by adenylate cyclase in adipocytes has been shown to desensitize upon chronic treatment with an A1 agonist as well (W. J. Parsons and G. L. Stiles J. Biol. Chem. Vol. 262 (1987) p. 841-847).
The compositions of this invention may be administered orally, intravenously, through the epidermis, bolus, nasally, by inhalation or by any other means known in the art for administering a therapeutic agents. The method of treatment comprises the administration of an effective quantity of the chosen compound, preferably dispersed in a pharmaceutical carrier. Dosage units of the active ingredient are generally selected from the range of 0.01 to 100 mg/kg, but will be readily determined by one skilled in the art depending upon the route of administration, age and condition of the patient.
Pharmaceutical compositions including the compounds of this invention, and/or derivatives thereof, may be formulated as solutions or lyophilized powders for parenteral administration. Powders may be reconstituted by addition of a suitable diluent or other pharmaceutically acceptable carrier prior to use. If used in liquid form the compositions of this invention are preferably incorporated into a buffered, isotonic, aqueous solution. Examples of suitable diluents are normal isotonic saline solution, standard 5% dextrose in water and buffered sodium or ammonium acetate solution. Such liquid formulations are suitable for parenteral administration, but may also be used for oral administration. It may be desirable to add excipients such as polyvinylpyrrolidinone, gelatin, hydroxycellulose, acacia, polyethylene glycol, mannitol, sodium chloride, sodium citrate or any other excipient known to one of skill in the art to pharmaceutical compositions including compounds of this invention. Alternatively, the pharmaceutical compounds may be encapsulated, tableted or prepared in an emulsion or syrup for oral administration. Pharmaceutically acceptable solid or liquid carriers may be added to enhance or stabilize the composition, or to facilitate preparation of the composition. Liquid carriers include syrup, peanut oil, olive oil, glycerin, saline, alcohols and water. Solid carriers include starch, lactose, calcium sulfate, dihydrate, teffa alba, magnesium stearate or stearic acid, talc, pectin, acacia, agar or gelatin. The carrier may also include a sustained release material such as glycerol monostearate or glycerol distearate, alone or with a wax. The amount of solid carrier varies but, preferably, will be between about 20 mg to about 1 gram per dosage unit. The pharmaceutical dosages are made using conventional techniques such as milling, mixing, granulation, and compressing, when necessary, for tablet forms; or milling, mixing and filling for hard gelatin capsule forms. When a liquid carrier is used, the preparation will be in the form of a syrup, elixir, emulsion or an aqueous or non-aqueous suspension. Such a liquid formulation may be administered directly or filled into a soft gelatin capsule.
The Examples which follow serve to illustrate this invention. The Examples are not intended to limit the scope of this invention, but are provided to show how to make and use the compounds of this invention.